首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3488篇
  免费   168篇
  国内免费   15篇
耳鼻咽喉   60篇
儿科学   297篇
妇产科学   52篇
基础医学   313篇
口腔科学   133篇
临床医学   300篇
内科学   711篇
皮肤病学   70篇
神经病学   146篇
特种医学   154篇
外科学   433篇
综合类   141篇
预防医学   165篇
眼科学   98篇
药学   356篇
中国医学   30篇
肿瘤学   212篇
  2023年   45篇
  2022年   118篇
  2021年   154篇
  2020年   86篇
  2019年   94篇
  2018年   160篇
  2017年   106篇
  2016年   135篇
  2015年   134篇
  2014年   178篇
  2013年   209篇
  2012年   255篇
  2011年   277篇
  2010年   158篇
  2009年   117篇
  2008年   133篇
  2007年   137篇
  2006年   131篇
  2005年   109篇
  2004年   77篇
  2003年   89篇
  2002年   60篇
  2001年   59篇
  2000年   51篇
  1999年   35篇
  1998年   46篇
  1997年   46篇
  1996年   23篇
  1995年   21篇
  1994年   27篇
  1993年   16篇
  1992年   23篇
  1991年   32篇
  1990年   31篇
  1989年   34篇
  1988年   44篇
  1987年   27篇
  1986年   26篇
  1985年   29篇
  1984年   8篇
  1983年   11篇
  1981年   9篇
  1980年   5篇
  1979年   23篇
  1978年   22篇
  1977年   10篇
  1976年   6篇
  1973年   5篇
  1969年   10篇
  1968年   5篇
排序方式: 共有3671条查询结果,搜索用时 15 毫秒
61.
The aim of the study was to demonstrate if 2% lidocaine hydrochloride with 1 : 200,000 epinephrine could provide palatal anesthesia in maxillary tooth removal with a single buccal injection. The subjects included in the clinical study were those requiring extraction of the maxillary third molar of either side. For the purpose of comparison, the sample was randomly divided into 2 main groups: group 1 (study group) included 100 subjects who were to receive a single injection before extraction, and group 2 (control group) included 100 subjects who were to receive a single buccal injection and a single palatal injection before extraction. After 5 minutes the extraction was performed. All patients were observed for Faces Pain Scale during extraction and asked for the same on a 100-mm visual analog scale after extraction. According to visual analog scale and Faces Pain Scale scores, when maxillary third molar removal without palatal injection (study group) and with palatal injection (control group) were compared the difference was not statistically significant (P > .05). Removal of maxillary third molars without palatal injection is possible by depositing 2 mL of 2% lidocaine hydrochloride with 1 : 200,000 epinephrine to the buccal vestibule of the tooth.Key Words: Maxillary third molar, Lidocaine hydrochloride with 1 : 200,000 epinephrine single buccal injection, Local anesthesiaAchieving excellent local anesthesia is the key to many dental treatments. Pain-free operating is an added benefit to the patient but also helps the operator to treat the patient in a calm, unhurried fashion.1 The removal of maxillary third molars is one of the most frequently performed procedures by dental surgeons. Indications for removal include common pathological conditions such as caries, buccal eruption with food impaction or cheek biting, and recurrent pericoronitis.2According to the literature, for the removal of maxillary third molars, anesthetic solution should be administered as either a greater palatine nerve block or local palatal infiltration plus either a posterior alveolar nerve block or a buccal infiltration.3 Palatal injections are frequently associated with some level of discomfort due to strong attachment of palatal mucosa to the bone and dense innervation of the palatal mucosa. Many studies reported that palatal injections are poorly tolerated by the majority of patients.35Initially there was inadequate evidence in the literature to support maxillary third molar removal with only buccal infiltration of local anesthesia,6 but now more studies have evaluated the bucco-palatal diffusion of local anesthesia in extractions with only buccal vestibular anesthesia, without palatal complementation.7,8Many techniques have been tried to reduce the discomfort of intraoral injections, including transcutaneous electronic nerve stimulation, topical anesthetic application, topical cooling of the palate, computerized injection systems, pressure administration, and eutectic mixture of local anesthetics. Some claim that articaine has a higher potential of diffusibility through soft and hard tissues, precluding palatal injection when maxillary third molars are extracted.7,9 In a comparative study between articaine and lidocaine, both solutions presented similar behavior and properties.10The aim of our study was to find out if lidocaine hydrochloride with epinephrine could provide palatal anesthesia in maxillary third molar removal without the need for a palatal injection.  相似文献   
62.
63.
Rationale: Long-term survival after lung transplantation is limited by infectious complications and by bronchiolitis obliterans syndrome (BOS), a form of chronic rejection linked in part to microbial triggers. Objectives: To define microbial populations in the respiratory tract of transplant patients comprehensively using unbiased high-density sequencing. Methods: Lung was sampled by bronchoalveolar lavage (BAL) and upper respiratory tract by oropharyngeal wash (OW). Bacterial 16S rDNA and fungal internal transcribed spacer sequencing was used to profile organisms present. Outlier analysis plots defining taxa enriched in lung relative to OW were used to identify bacteria enriched in lung against a background of oropharyngeal carryover. Measurements and Main Results: Lung transplant recipients had higher bacterial burden in BAL than control subjects, frequent appearance of dominant organisms, greater distance between communities in BAL and OW indicating more distinct populations, and decreased respiratory tract microbial richness and diversity. Fungal populations were typically dominated by Candida in both sites or by Aspergillus in BAL but not OW. 16S outlier analysis identified lung-enriched taxa indicating bacteria replicating in the lower respiratory tract. In some cases this confirmed respiratory cultures but in others revealed enrichment by anaerobic organisms or mixed outgrowth of upper respiratory flora and provided quantitative data on relative abundances of bacteria found by culture. Conclusions: Respiratory tract microbial communities in lung transplant recipients differ in structure and composition from healthy subjects. Outlier analysis can identify specific bacteria replicating in lung. These findings provide novel approaches to address the relationship between microbial communities and transplant outcome and aid in assessing lung infections.  相似文献   
64.
65.
66.
In the present report, an environmentally benign magnetically recoverable nickel(ii)-based nanoreactor as a heterogeneous catalyst has been developed via a template free approach. The catalytic performance of the synthesized catalyst is assessed in the confined oxidative coupling of arenethiols with arylhydrazines to form unsymmetrical diaryl sulfides under aerobic conditions. The salient features of our protocol include oxidant- and ligand-free conditions, use of water as a green solvent, room temperature and formation of nitrogen and water as the only by-products. Moreover, a broad range of functional groups are tolerated well and provide the corresponding diaryl sulfides in moderate to good yields. Moreover, the heterogeneous nature of the catalyst permits facile magnetic recovery and reusability for up to seven runs, making the present protocol highly desirable from industrial and environmental standpoints.

An environmentally benign nickel(ii)-based magnetic nanoreactor has been developed for oxidative coupling of arenethiols with arylhydrazines to form unsymmetrical diaryl sulfides in water at room temperature.  相似文献   
67.
A simple synthetic strategy has been developed for the synthesis of 2- and 1-alkyl/aryl/dialkylaminoquinolines and isoquinolines from the easily available quinoline and isoquinoline-N-oxides, different amines, triflic anhydride as activating agent and acetonitrile as solvent in a one-pot reaction under metal-free conditions at 0 °C to room temperature.

A synthetic strategy has been developed for synthesis of 2 and 1-aminoquinolines and isoquinolines from quinoline and isoquinoline-N-oxides, amines and triflic anhydride in acetonitrile at 0 °C to room temperature.  相似文献   
68.
69.
Objective:Metaphyseal-diaphyseal fractures of the distal radius are a major treatment dilemma and orthopaedic surgeons have to pay due consideration to restoration of anatomy of distal radius together with rotation of the radial shaft and maintenance of radial bow and interosseous space.We performed this study to evaluate the clinic-radiological outcome of metaphyseal-diaphyseal fractures of the distal radius treated with long volar locking plates.Methods:This prospective study involved 27 patients (22 males and 5 females) with metaphyseal-diaphyseal fracture of the distal radius.Their mean age was (30.12±11.48) years (range 19-52 years) and the follow-up was 26.8 months (range 22-34 months).All patients underwent open reduction and internal fixation with a long volar locking plate.According to AO/OTA classification,there were 7 type A3,13 type C2 and 7 type C3 fractures.Subjective assessment was done based on the disabilities of the arm,shoulder and hand (DASH) questionnaire.Functional evaluation was done by measuring grip strength and range of motion around the wrist and the radiological determinants included radial angle,radial length,volar angle and ulnar variance.The final assessment was done according to Gartland and Werley scoring system.Results:Postoperative radiological parameters were well maintained throughout the trial,and there was significant improvement in the functional parameters from 6 weeks to final follow-up.The average DASH scores improved from 37.5 at 6 weeks to 4.2 at final follow-up.Final assessment using Gartland and Werley scoring system revealed 66.67%(n=l8) excellent and 33.33% (n=9) good results.There was one case of superficial infection which responded to antibiotics and another carpel tunnel syndrome which was managed conservatively.Conclusion:Volar locking plate fixation for metaphyseal-diaphyseal fractures of distal radius is associated with excellent to good functional outcome,early rehabilitation and minimal complications.  相似文献   
70.
Objective:To present our experience in treatment of difficult ununited long bone fractures with locking plate.Methods:Retrospective evaluation of locking plate fixation in 10 difficult nonunions of lon...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号